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serum unconjugated primary and secondary bile acids in patients with cholangiocarcinoma and hepatocellular carcinoma.serum unconjugated primary bile acids (cholic acid, chenodeoxycholic acid), secondary bile acids (lithocholic acid, deoxycholic acid), conjugated primary bile acids (glycocholic acid, glycohenodeoxycholic acid, taurocholic acid, taurochenodeoxycholic acid) and total bile acids were measured in 25 and 75 male patients with cholangiocarcinoma and hepatocellular carcinoma respectively. twenty-one healthy male volunteers served as controls. other biochemical parameters, i.e. bilirubin, transaminases ...19902161896
a high frequency of hepatobiliary disease and suspected cholangiocarcinoma associated with heavy opisthorchis viverrini infection in a small community in north-east thailand.a group of 87 adults from a small village in north-east thailand was chosen to undergo ultrasound investigation based on their intensity of infection with the liver fluke, opisthorchis viverrini, or clinical status (history of jaundice, current hepatomegaly). from this group, 8 cases of suspected early cholangiocarcinoma were found, and the diagnostic features of 6 of the 8 were confirmed by computerized tomography scan and endoscopic retrograde cholangiopancreatography. in addition, several cas ...19902177578
immunological analysis of opisthorchis and clonorchis antigens.immunoreactive components of opisthorchis viverrini and clonorchis sinensis were analysed by enzyme-linked immunosorbent assay (elisa), radioimmunoprecipitation and immunoblotting. somatic extracts from these two liver flukes as well as from other related parasites, together with the metabolic products, were tested for their reactivities with sera from patients with opisthorchiasis and clonorchiasis. a significant cross-reactivity in the elisa was noted between opisthorchis and clonorchis. immun ...19902201720
opisthorchis viverrini: finding and recognition of the fish host by the cercariae.the cercaria of opisthorchis viverrini finds and recognizes its fish host by using at least four steps of behavioral patterns. (1) dispersal and selection of plant-free water microhabitat are achieved by intermittent swimming behavior with positive phototactic orientation. (2) attachment to the host is stimulated by water currents and a hydrophilic component of fish skin surface which has a molecular weight of more than 30,000. this component is sensitive to digestion with hyaluronidase and seem ...19902226703
monoclonal antibodies against opisthorchis viverrini antigens.monoclonal antibodies (moab) were produced against somatic antigens of adult human liver fluke opisthorchis viverrini. earlier studies attached diagnostic potential to an 89-90 kd antigen present in both somatic extracts and in vitro culture supernatants as well as to the abundant 16-17 kd tegumental protein doublet. mice made excellent immune responses to low dose somatic extract adsorbed onto nitrocellulose or to the 80-95 kd region of sds gel western blots. the antigen specificities of hybrid ...19902255563
health status of thai volunteers in a cholera vaccine trial.one hundred and seventy-one male adults were screened in recruitment of volunteers for a cholera vaccine trial. a full medical history and a physical examination were performed on each subject. the percentages of subjects vaccinated against cholera and typhoid within twelve months were 4 and 1 per cent respectively, while 88 and 15 per cent respectively had been vaccinated more than a year. biochemical screening revealed abnormal liver function tests in 40.7 per cent, specifically alkaline phosp ...19902280201
species determination of eggs of opisthorchiid and heterophyid flukes using scanning electron microscopy.eggs of opisthorchiid flukes have very characteristic muskmelon-like surface structure of their shells and can be differentiated using this mark from eggs of heterophyid flukes. surface structure and morphological details in operculum and abopercular end can be observed using scanning electron microscopy. eggs recorded very often in stool of laotians belong mostly to opisthorchis viverrini and sporadically to metagonimus yokogawai.19902337251
diagnosis of opisthorchiasis by enzyme-linked immunosorbent assay using partially purified antigens.opisthorchis viverrini antigens were partially purified from adult worms collected from liver and extrahepatic biliary system of infected hamsters. tegument fraction was obtained by chemical extraction, whereas other fractions were purified by sephadex g-200 gel filtration chromatography. five fractions of o. viverrini antigens were obtained, namely tegument extract, somatic extract, fraction 1 (p1), fraction 2 (p2) and fraction 3 (p3), respectively. the enzyme-linked immunosorbent assay techniq ...19902393450
liver cancer in thailand. i. a case-control study of cholangiocarcinoma.potential risk factors for cholangiocarcinoma were investigated in a case-control study among inhabitants of north-east thailand, which included 103 cases from 3 hospitals, with age- and sex-matched controls. a clear association with past or present infection with opisthorchis viverrini, as indicated by raised serum antibodies, was found (o.r. 5.0), and at least two-thirds of cases can be attributed to this cause. the results suggest that males may be at higher risk than females. there was no as ...19911645697
endogenous nitrosamines and liver fluke as risk factors for cholangiocarcinoma in thailand.cholangiocarcinoma (cca) is one of the most prevalent cancers in north-east thailand and has been associated with infestation by the liver fluke opisthorchis viverrini (ov). two samples of 12-h overnight urine (after dosing with 500 mg proline and 200 mg ascorbic acid or 500 mg proline alone) were collected from about 100 inhabitants in five contrasting incidence areas for cca and hepatocellular carcinoma. the incidences of cca and hepatocellular carcinoma were not correlated with either the amo ...19911649794
opisthorchis viverrini infestation and endogenous nitrosamines as risk factors for cholangiocarcinoma in thailand.cholangiocarcinoma (cca) is one of the most common cancers in north-east thailand and has been associated with infestation by the liver fluke opisthorchis viverrini (ov). two samples of 12-hr overnight urine (after dosing with proline and ascorbic acid or proline alone) were collected from 20 inhabitants from each of 5 contrasting incidence areas for cca. the incidence of cca was not correlated with either the amount of npro or other nitrosamino acids, endogenous nitrosation potential (differenc ...19911650329
the role of infection by opisthorchis viverrini, hepatitis b virus, and aflatoxin exposure in the etiology of liver cancer in thailand. a correlation study.the incidence of the two principle types of liver cancer (hepatocellular carcinoma and cholangiocarcinoma) in five different areas of thailand was compared with the prevalence of exposure to the main risk factors in samples of the population. cholangiocarcinoma showed striking variations in incidence, which correlated closely with markers of exposure to the liver fluke, opisthorchis viverrini. however, there was little geographic variation in incidence of hepatocellular carcinoma or in prevalenc ...19911657355
a histopathologic study of 61 cases of peripheral intrahepatic cholangiocarcinoma.the histopathological study of 61 cases of peripheral intrahepatic cholangiocarcinoma was reported. of the 5 autopsied livers and 13 surgically resected livers, 89 per cent showed massive gross appearance, 94 per cent contained opisthorchis viverrini or showed evidence of previous opisthorchiasis. gall stones were found in 7 cases (11.5%), common bile duct stones were found in one case. the tumors were classified into well differentiated, less differentiated and uncommon types (adenosquamous, an ...19911665850
multistage carcinogenesis of liver-fluke-associated cholangiocarcinoma in thailand.in northeast thailand, the traditional habit of eating ground, raw freshwater and salt-fermented fish on a daily basis results in a local population repeatedly exposed to both liver fluke (opisthorchis viverrini) infection and consuming nitrosamine-contaminated food from early in life. epidemiological studies have revealed a coincident high prevalence of cholangiocarcinoma in this region and we have demonstrated in animal models that dietary contamination with nitrosamines and opisthorchiasis ar ...19911668894
production and characterization of monoclonal antibodies against the excretory-secretory antigen of the liver fluke (opisthorchis viverrini).monoclonal antibodies (moab) were produced against a major soluble metabolic product (excretory-secretory, es) of opisthorchis viverrini. the latter was obtained in a form of spent culture medium in which the adult flukes had been maintained in vitro. the moab produced were exclusively associated with either igg or igm isotypes. when screened against a panel of parasite antigens by indirect elisa, these moab exhibited three patterns of reactivity. approximately 50% of the moab were highly specif ...19911717391
detection of opisthorchis viverrini by monoclonal antibody-based elisa and dna hybridization.monoclonal antibody-based enzyme-linked immunosorbent assay and dna hybridization techniques were developed and evaluated for their potential in the detection of opisthorchis viverrini infection in humans. a mixture of three igg1 monoclonal antibodies (mab) specific for the 89 kda metabolic product of o. viverrini was captured on a microtiter plate by rabbit anti-mouse igg and used in a sandwich elisa for the detection of parasite antigen. the 89 kd component bound to the mab was detected with b ...19912012257
immune responsiveness and parasite-specific antibody levels in human hepatobiliary disease associated with opisthorchis viverrini infection.opisthorchis viverrini infection is associated with human hepatobiliary disease and cholangiocarcinoma, but the role of the immune response in the pathogenesis of infection is unclear. here ultrasonography was used to examine the biliary tracts of residents from an endemic community. delayed-type hypersensitivity responses to unrelated antigens, and fluke-specific igg and iga levels in serum of this group were also examined. relationships between immunological parameters, intensity of infection ...19912025950
characterization of the opisthorchis viverrini genome.the methylations of trematode genomic dna were analyzed using restriction enzymes and southern blot hybridization. restriction enzymes mspi, hpaii, hhai were used to probe cpg methylation while mboi, sau3a, dpni were used for a methylation. the results revealed that opisthorchis viverrini, fasciola gigantica and gigantocotyle siamensis had neither cpg nor a methylations. the presence of highly repeated dna elements was also demonstrated in o. viverrini genomic dna.19912050985
human opisthorchis and haplorchis infections in laos.a study of the epidemiology of trematode infections was carried out in vientiane province, laos, comprising examination of snails, fish, cats, and human stools. opisthorchis viverrini cercariae were found in the snail bithynia siamensis goniomphalus (bithyniidae) and haplorchis taichui cercariae in tarebia granifera (thiaridae). o. viverrini metacercariae were recorded in the flesh of 7 species of cyprinid fish; metacercariae of the heterophyid fluke haplorchis taichui were found in 4 species of ...19911755066
molecular analysis of t and b cell repertoires in mice immunized with opisthorchis viverrini antigens.b10 mice were immunized with an opisthorchis viverrini somatic extract and then their responses were analyzed. the antigenic fractions of the extract were separated by sds-polyacrylamide gel electrophoresis, electroblotted to nitrocellulose membranes and solubilized for use in lymphocyte culture. antibody specificity was also visualized by immunoblotting using immunized mouse sera. the mr of the main immunogenic fractions for t cells ranged from 28 to 46 kda, whereas those recognized by antibodi ...19911757200
isolation and characterization of opisthorchis viverrini specific dna probe.an opisthorchis viverrini specific repetitive dna fragment was isolated from the o. viverrini genome. the cloned fragment, herein designated pov-a6, contained tandemly repeated 334 bp o. viverrini dna and has the potential to be a highly specific and sensitive dna probe. radioactively labelled pov-a6 could detect as little as 25 pg of its own genomic dna and five purified eggs by dot-blot hybridization. the presence of 50 o. viverrini eggs could be readily detected in samples containing faecal m ...19911779978
specific monoclonal antibodies to opisthorchis viverrini.a balb/c mouse was immunized with a crude soluble antigen of opisthorchis viverrini adult worms (ovaa) over a period of 7 months. spleen cells from the immune mouse were fused with sp2/0 myeloma cells. among the 264 tissue culture wells containing the fused cells, cells of 96 wells (36%) produced antibodies to the immunizing agent. antibodies produced by cells in several wells reacted with antigens from other species of parasite. cells of 17 wells produced antibodies specific only to ovaa, thus ...19911787041
quantitative post-mortem study of opisthorchis viverrini in man in north-east thailand.the results of an autopsy study of opisthorchis viverrini infection in 181 accident subjects in northeast thailand are presented. the age-prevalence profiles were similar whether determined by faecal examination for parasite eggs or by recovery of worms from the liver. the prevalence increased rapidly with age and reached a plateau at 70-80% in adults. the overall prevalence estimated by faecal examination was 69.2%, while that measured by worm recovery was 79.2%. the average intensity of infect ...19911801350
comparative studies on the morphology of the eggs of opisthorchis viverrini and lecithodendriid trematodes.iodine staining and scanning electron microscopy were used to determine the morphological features distinguishing opisthorchis viverrini from lecithodendriid eggs in human feces. the embryonated eggs of lecithodendriid trematodes differ from o. viverrini by the presence of an iodophilic body, a large mass at the posterior end of miracidium that stains brown in 0.2% iodine solution and the curved miracidium of phaneropsolus bonnei. all forms of lecithodendriid eggs can be differentiated from thos ...19911820653
eggshell morphology of the small eggs of human trematodes in thailand.light and scanning electron micrographs of opisthorchis viverrini, haplorchis taichui, h. pumilio, a phaneropsolus bonnei, and prosthodendrium molenkampi eggs were studied. under light microscopy. o. viverrini eggs had rough eggshells and prominent shoulders. h. taichui, h. pumilio were similar in shape and had smooth eggshells and prominent shoulders. h. pumilio eggs were bigger than h. taichui eggs. p. bonnei and p. molenkampi eggs had smooth eggshells and indistinct shoulders. p. bonnei eggs ...19911820654
differential diagnosis of opisthorchiid and heterophyid metacercariae (trematoda) infecting flesh of cyprinid fish from nam ngum dam lake in laos.the examination of flesh of 313 cyprinid fish from the nam ngum water reservoir in vientiane province, laos, revealed the presence of four morphologically similar opisthorchiid and heterophyid metacercariae of medical importance. the following morphological characters, visible under dissecting microscope with low magnification, were typical of trematodes recorded in fish: (1) opisthorchis viverrini, the liver fluke, has oval cysts containing quickly moving c-shaped metacercariae provided with a ...19911822880
serological differentiation of human small fluke infections using opisthorchis viverrini and haplorchis taichui antigens.sera from 642 inhabitants of vientiane province (laos) were examined by enzyme-linked immunosorbent assay (elisa) using cytoplasmic and membranous antigens prepared from adult worms. worms of opisthorchis viverrini originated from liver of dissected cats, haplorchis taichui were obtained from a stool specimen of a laotian patient after praziquantel treatment. the sera were divided into five groups according to the intensity of infection expressed as egg count per gram of patients stool (epg). co ...19911822881
immunodiagnosis of opisthorchiasis.monoclonal antibody-based enzyme-linked immunosorbent assay and dna dot blot hybridization techniques were developed and evaluated for their potential in the detection of opisthorchis viverrini. a mixture of igg monoclonal antibodies specific for the 89 kda metabolic product of o. viverrini was captured on a microtiter plate by rabbit anti-mouse igg and used in a sandwich elisa for the detection of soluble parasite antigen in the feces of patients with opisthorchiasis. as little as 0.1 ng of the ...19911822882
preliminary estimates of economic impact of liver fluke infection in thailand and the feasibility of irradiation as a control measure.liver fluke infection by opisthorchis viverrini is the leading cause of food-borne parasitic disease in thailand. approximately one third of the population in the northeastern region of the country, ie, 6-7 million, are infected by this parasite through the habit of consuming raw or insufficiently cooked freshwater fish, especially those of cyprinoid family. a recent survey showed that 60% of the work force in the northeast between the age of 15 and 60 is infected. the estimated wage loss of thi ...19911822933
current status of food-borne parasitic zoonoses in laos.stool samples from a total of 1,008 persons were examined for intestinal parasites during a comprehensive study on the epidemiology of small fluke infections in laos. the prevalence of small fluke eggs in the stool was seen to peak at age 20 years, particularly in men from villages (90.4%). three quarters of infections belong to the category of light infections and only 0.6% to the category of very heavy according to eggs per gram of feces (epg). the highest epg was in the 11-15 year age group. ...19911822938
relationship between faecal egg count and worm burden of opisthorchis viverrini in human autopsy cases.the relationship between faecal examination for egg output and worm burden of opisthorchis viverrini in man of 181 autopsy cases from northeast thailand is described. diagnosis of the parasite infection by stool examination for the presence of eggs was less sensitive than the worm recovery technique. using stoll's dilution and formalin-ether technique, no eggs were detected in the faeces of 20 cases harbouring low worm burdens (less than 20 worms). the quantitative faecal egg count by stoll's di ...19911852493
opisthorchis viverrini: relationships between egg counts, worms recovered and antibody levels within an endemic community in northeast thailand.three techniques for estimating the intensity of opisthorchis viverrini infection in individuals from a northeast thai community are compared. egg counts were determined using a quantitative formalin/ethyl acetate technique, worm burdens were estimated by expulsion chemotherapy and antibody levels were measured by elisa. log-transformed worm and egg counts were closely correlated (r = 0.80), suggesting that both measurements provide good assessments of relative intensity of infection. however, n ...19911852494
possible effect of infection with liver fluke (opisthorchis viverrini) on the monitoring of urine by enzyme-linked immunosorbent assay for human exposure to aflatoxins.several laboratories have initiated studies to assess human exposure to aflatoxin at an individual level by measuring aflatoxin metabolites in the urine by immunoassay. the fact that the antibodies recognize a variety of metabolites, albeit with differing affinities, means that any environmental factor that modifies the pattern of urinary metabolites associated with a given exposure could affect quantification in immunoassay. we have examined two such possible effects: (i) the pattern of metabol ...19911855928
penetration of stimuli of fish skin for acanthostomum brauni cercariae.the cercaria of acanthostomum brauni penetrates the skin of its fish host in response to a combination of two chemical signals from the fish skin surface: free fatty acids and a macro-molecular mucus component. the latter seems to be a protein, as the penetration-stimulating activity of fish skin surface mucus is eliminated by digestion with proteinase, but not by digestion with glycosidases, nor by a removal of glycosaminoglycans. these penetration-stimulating host signals differ from the glyco ...19911903874
nucleotide sequence of the small subunit ribosomal rna-encoding gene from opisthorchis viverrini.the complete nucleotide (nt) sequence of the small subunit ribosomal rna-encoding gene of opisthorchis viverrini reported in this study is the first nt sequence reported for a trematode. the gene is 1992 nt long and has a g + c content of 50.94%. it is made up of alternated constant and variable regions that are similar to the gene organization of other eukaryotes. it is also of interest to note an unexpectedly high degree of sequence homology between o. viverrini and human genes.19911937023
distribution patterns of opisthorchis viverrini within a human community.this paper describes patterns of infection with opisthorchis viverrini within a human community assessed by egg count, parasite-specific antibody levels and worm burden determined by expulsion chemotherapy. all three measurements increased significantly with age, reaching a plateau in young adults. there were no significant sex-associated differences in the prevalence or intensity of infection, antibody levels, or in the frequency of heavy worm burdens. a striking 81.5% of the total opisthorchis ...19911945529
influence of water current on the distribution of opisthorchis viverrini infection in northeastern villages of thailand.the prevalences of opisthorchis viverrini infection in the villages on the banks of rivers and those far from the rivers were studied in loei and nong khai provinces in thailand. most of the people examined in the present study were agriculturalists. the overall prevalence of o. viverrini infection was 41.3%. the prevalence of infection in males and in females in the villages far from the rivers were 52.6% and 51.7%, respectively, while the percent of people in the villages on the banks with inf ...19911948268
laboratory studies on host-parasite relationship of bithynia snails and the liver fluke, opisthorchis viverrini.the infection rate of bithynia snails to opisthorchis viverrini eggs was studied in relation to exposure intensity, age and species of host. it was found that 50 miracidial eggs per snail yielded the highest percentage of living surviving positive snails. bithynia funiculata and bithynia siamensis siamensis were highly susceptible to o. viverrini, about four to seven times higher than bithynia siamensis goniomphalos. young snails, 1-3 months old, appeared more susceptible than old snails.19911948284
specific and cross-reactive monoclonal antibodies to the 89-kda antigen of opisthorchis viverrini. 19921283231
larval stages of medically important flukes (trematoda) from vientiane province, laos. part ii. cercariae.the cercariae of five flukes, which are potential human parasites, opisthorchis viverrini (family opisthorchiidae), haplorchis taichui (heterophyidae), schistosoma spindale (schistosomatidae), fasciolopsis buski, and fasciola gigantica (fasciolidae) were found in freshwater snails from laos. the cercariae of the above species, recorded in laos for the first time, are illustrated and their morphology is briefly described. the snail helicorbis umbilicalis represents a new intermediate host of f. b ...19921290378
study on the surface morphology of the developmental stages of the liver fluke, opisthorchis viverrini (trematoda: opisthorchiidae).the external morphology of some developmental stages of the fluke opisthorchis viverrini (trematoda: opisthorchiidae), parasitizing humans in southeast asia was studied for the first time using electron microscopy. the surface structure of the egg, as well as the rediae, cercaria, metacercaria, and adult found in naturally infected hosts from laos are described herein and their morphological characteristics discussed.19921290379
relationship between intensity of opisthorchis viverrini infection and hepatobiliary disease detected by ultrasonography.twenty-four locality-, age- and sex-matched groups of village residents with no light, moderate and heavy opisthorchis viverrini infection were examined by ultrasonography. highly significant differences were observed between the groups in the relative size of the left lobe of the liver and the fasting and post-meal size of the gall-bladder. in addition, indistinct gall-bladder wall, the presence of gall-bladder sludge and strongly enhanced portal vein radicle echoes were most frequently observe ...19921311966
opisthorchis viverrini infection in northeast thailand and its relationship to cholangiocarcinoma. 19921327263
histomorphological characteristics of cholangiocellular carcinomas in northeast thailand, where a region infection with the liver fluke, opisthorchis viverrini is endemic.northeast thailand has a very high incidence rate of intrahepatic biliary tumors which is believed to closely related to infestation with the liver fluke, opisthorchis viverrini. this study was conducted to ascertain whether there are any phenotypic differences in such tumors between northeast thailand and japan, a country free of liver flukes. forty one intrahepatic cholangiocarcinomas from patients in northeast thailand were histopathologically compared with 39 lesions collected in japan. the ...19921334615
cholangiocarcinomas in japanese and thai patients: difference in etiology and incidence of point mutation of the c-ki-ras proto-oncogene.point-mutational activation of the c-ki-ras proto-oncogene has been shown to be rare in human hepatocellular carcinoma, the most common primary liver cancer and one usually associated with chronic viral infection. to reveal the association of c-ki-ras activation with cholangiocarcinogenesis under different etiological backgrounds, the incidence of point mutation at codons 12 and 13 of the c-ki-ras proto-oncogene was examined in three groups of human liver cancers with differentiation to biliary ...19921336666
prevalence and intensity of opisthorchis viverrini in rural community near the mekong river on the thai-laos border in northeast thailand.the prevalence and intensity of opisthorchis viverrini in fourteen villages in nakhon-phanom province, northeast, thailand have been investigated. overall prevalence of o. viverrini infection was 66.4 per cent in a total population of 2,412 individuals. the prevalence was 18.5 per cent in children under 5 years, 38.9 per cent in those aged 5-9 years, and ranged from 64.9 per cent to 82.2 per cent in the age group above 10 years. the intensity of o. viverrini infection increased with age. the mea ...19921402447
development of immune-complex glomerulonephritis and amyloidosis in syrian golden hamsters infected with opisthorchis viverrini.renal disease associated with opisthorchis viverrini infection was investigated in syrian golden hamsters. on the fourth week after infection with 100 viable metacercariae; anti-tegumental membrane antibodies were detected in the sera by immunofluorescence antibody technic and by enzyme-linked immunosorbent assay. six weeks after infection tegumental and anti-tegumental membrane immune-complex and amyloid fibrils were found in the glomeruli. amyloid was characterized to be aa protein. acute prol ...19921402485
malacological survey in the sirikit reservoir, the largest earthfilled dam in thailand.ten species of freshwater molluscs were found in a malacological survey in the sirikit reservoir in 1985. among these species, tricula aperta or neotricula aperta, intermediate host of human schistosomes, bithynia (digoniostoma) siamensis goniomphalos and b. (d.) funiculata, the first intermediate host of opisthorchis viverrini were not found. it is revealed that most of the habitats in the sirikit reservoir are not suitable for the survival and colonization of molluscs. thus few species of edib ...19921439988
control of opisthorchis viverrini cercariae using the copepod mesocyclops leuckarti. 19921439992
cloning and characterization of ribosomal rna genes from opisthorchis viverrini.the ribosomal dna (rdna) unit of the liver fluke opisthorchis viverrini has been cloned and characterized. the results demonstrated that the total length of this unit is approximately 13 kb, containing 4.2 kb of large subunit (lsu) rdna, 2.0 kb of small subunit (ssu) rdna, 1.0 kb of transcribed spacer dna and 5.8 kb of non-transcribed + external transcribed spacer dna. examination of the non-transcribed spacer region between different rdna units showed variation in the restriction sites rather t ...19921594296
separation and characterization of adult worm proteins and glycoproteins from the liver fluke opisthorchis viverrini.detailed studies of liver fluke proteins and antigens are necessary to facilitate further investigation of the human immune responses to these parasites. accordingly, opisthorchis viverrini antigens were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (sds-page) and immunoblotting. we initially encountered excessive background smearing, vertical streaking, and indistinct bands that were similar to problems previously described by investigators studying this and other tremat ...19921635026
comparative morphology of eggs of the haplorchiinae (trematoda: heterophyidae) and some other medically important heterophyid and opisthorchiid flukes.the egg morphology of the following medically important small flukes from southeast asia and far east were studied: opisthorchis viverrini, clonorchis sinensis (opisthorchiidae), haplorchis taichui, h. pumilio, h. yokogawai, stellantchasmus falcatus and metagonimus sp. (heterophydiae). this study revealed a great intraspecific variability and interspecific similarity in size and shape of eggs. the eggs shape does not seem to be suitable for species identification. on the other hand, biometrical ...19921644359
detection of opisthorchis viverrini antigens in stools using specific monoclonal antibody.detection of opisthorchis viverrini antigens in stools using specific monoclonal antibody. international journal for parasitology 22: 527-531. a sandwich enzyme-linked immunosorbent assay (elisa) was developed for detecting opisthorchis viverrini antigen in faecal extracts of four groups of individuals. these were 24 patients with o. viverrini infection only (group 1), 31 patients with o. viverrini and other parasitic infections (group 2), 141 patients with other parasitic infections (group 3) a ...19921644529
repeated exposure to opisthorchis viverrini and treatment with the antihelminthic praziquantel lacks carcinogenic potential.the effects of repeated praziquantel administration, subsequent to infection and reinfection with opisthorchis viverrini (ov), on lesion development in the syrian hamster liver were investigated. five applications of the antihelminthic drug were made (300 mg/kg body wt, i.g.), each time approximately 5 weeks after dosing with 60-80 ov metacercariae at weeks 0, 8, 16, 24 and 32. the animals were then maintained until week 40 when they were killed; histopathological investigation revealed no signi ...19921740024
opisthorchis viverrini and cholangiocarcinoma in northeast thailand.population-based research is beginning to show clearly the devastating impact that opisthorchis viverrini infection has on the laos-descendent population of northeast thailand who love to eat uncooked meat and fish, one of which being the parasite's intermediate host: cyprinoid fish. here, melissa haswell-elkins, paiboon sithithaworn and david elkins discuss the parasite's life cycle and epidemiology, highlighting the close relationship between this infection and bile duct carcinoma, which is a ...199215463578
promotion of cholangiocarcinogenesis in the hamster liver by bile duct ligation after dimethylnitrosamine initiation.administration of hepatocarcinogenic nitrosamines before or after infection with the liver fluke, opisthorchis viverrini (ov), results in marked development of cholangiocellular and hepatocellular precancerous and cancerous lesions in the hamster liver. the promoting effects of ov are believed to be exerted either mechanically, chemically or immunologically. to test the influence of possible mechanical effects, syrian hamsters were initiated with a single i.p. injection of dimethylnitrosamine (d ...19938242874
trematode infections. opisthorchiasis, clonorchiasis, fascioliasis, and paragonimiasis.the parasitic diseases of the liver and lung are caused by trematodes or flukes--opisthorchis viverrini, o. felineus, fasciola hepatica, and paragonimus westermani. humans get infected by eating the second intermediate host of the fluke, for example, fish, crab, or water plant. the disease runs a chronic course. the diagnosis is made by the recover of eggs in stools or sputum, or by serodiagnosis. praziquantel is the drug of choice except in falcioliaisis.19938254167
cholangiocarcinoma: epidemiology, mechanisms of carcinogenesis and prevention.cholangiocarcinoma is a relatively rare cancer; worldwide it accounts for an estimated 15% of liver cancers. in most areas, the etiology is rather obscure, and identified risk factors such as hepatolithiasis, inflammatory bowel disease, and exposure to thorotrast can account for only a small proportion of cases. in certain areas of southeast and eastern asia, however, incidence rates are very high, and here there is a strong association with infection with the liver flukes clonorchis sinensis an ...19938268770
opisthorchis viverrini: changes of the tegumental surface in newly excysted juvenile, first-week and adult flukes.the tegumental surface of the newly excysted juvenile, first-week and adult stages of a human liver fluke, opisthorchis viverrini, was studied by scanning electron microscopy. the surface of the newly excysted juvenile is characterized by circumferentially arranged ridges alternated with troughs which bear rows of spines encircling the body. these spines are characterized by the shapes of their edges: the first type with serrated edge appears on the anterior part, and the second type with single ...19938314365
reversal of biliary tract abnormalities associated with opisthorchis viverrini infection following praziquantel treatment.we recently demonstrated a number of biliary tract abnormalities associated with moderate to heavy opisthorchis viverrini infection among 95 selected village residents in north-east thailand, who were treated with praziquantel immediately after initial examination and re-examined by abdominal ultrasonography 10 months later. dramatic improvement in the gall-bladder status of previously infected individuals was observed, including reduction of gall-bladder length and width and regained contractib ...19938337727
imported opisthorchis viverrini and parasite infections from thai labourers in taiwan.in order to determine the prevalence of intestinal parasites among labourers from thailand in taiwan, the stool samples from 1364 thai labourers were examined by the formalin-ether concentration method and 18.0% were found to be infected with one or more parasites. the infection rates of hookworm, opisthorchis viverrini, strongyloides stercoralis, enterobius vermicularis, ascaris lumbricoides, hymenolepis nana, capillaria philippinensis, schistosoma japonicum, echinostoma sp., entamoeba coli, gi ...19938354853
precancerous lesions of the biliary tree.malignant tumors may arise from any portion of the biliary tree. the term cholangiocarcinoma (cc) applies to both intra- and extrahepatic tumors. more than 95% of these tumors are adenocarcinomas. differentiation between cc and metastatic adenocarcinoma represents a difficult task for the pathologist. the presence of an intratumoral mini-ductal plate, and in situ carcinoma in bile ducts near the tumor and modulation from the bile duct towards parenchymal liver cells represent the major criteria ...19938389160
ultrastructural hepatic alterations in hamsters and jirds after experimental infection with the liver fluke opisthorchis viverrini.changes in the hepatocytes of male hamsters (mesocricetus auratus) and jirds (meriones unguiculatus) at 220 days after experimental infection with the liver fluke opisthorchis viverrini were studied by light and electron microscopy. the hepatocytes of the control group were characterized by an intracellular compartmentation. a globular nucleus was located centrally. the main features of the perinuclear zone were the cisternae of the rough endoplasmic reticulum (rer) and interjacent mitochondria, ...19938415540
time-dependent modulation of liver lesion development in opisthorchis-infected syrian hamster by an antihelminthic drug, praziquantel.in the north-east of thailand, repeated antihelminthic therapy has been introduced for control of the opisthorchiasis known to be a major risk factor for cholangiocellular carcinomas. what influence this may have on tumorigenesis, however, remains unclear. the effects of administration of praziquantel, an antihelminthic drug, at different time points subsequent to infection with opisthorchis viverrini (ov) on 2,2'-dihydroxy-di-n-propylnitrosamine (dhpn)-initiated lesion development in the liver ...19938463130
field trials in the control of opisthorchis viverrini with an integrated programme in endemic areas of northeast thailand.a control programme of opisthorchiasis was carried out for three years in three villages of northeast thailand in order to compare the effectiveness of two intervention measures. the intervention measures employed were to give praziquantel treatment to all infected people either once (village i) or twice (village ii) per year with the integration of regular health education and sanitation improvement. a control village (village iii) received no intervention during the study. sampling of the popu ...19938488064
studies on lophocercous cercariae from bithynia siamensis goniomphalus (prosobranchia: bithyniidae).cercariae from bithynia siamensis goniomphalus were studied in an area endemic for opisthorchiasis. snails emitted different types of cercariae when shedding was induced by illumination. in addition to two lophocercous cercariae, a monostome cercaria (probably notocotylus sp), two different furcocercariae and a xiphidiocercaria were found. two similar types of lophocercous cercariae were distinguishable and one could be identified as opisthorchis viverrini. to date the cercaria of o. viverrini h ...19937939943
pharmacokinetics of praziquantel in patients with opisthorchiasis.the pharmacokinetics of praziquantel was investigated in 9 thai male patients with asymptomatic opisthorchiasis (stool positive) and 9 patients (6 males, 3 females) with moderately advanced infection (hepatomegaly). the geometric means of the pretreatment opisthorchis viverrini egg count in these patients were 2,950 vs 4,468 eggs per gram of stool. the results indicate the impairment of metabolism of praziquantel in the moderately advanced stage opisthorchiasis. the pharmacokinetics of the drug ...19937939947
association of antibodies to opisthorchis viverrini with hepatobiliary disease in northeastern thailand.the association between opisthorchis viverrini infection and hepatobiliary disease was studied in northeastern thailand. positive rates of o. viverrini infection and antibody titers to o. viverrini adult worm extracts, which were determined by enzyme-linked immunosorbent assay (elisa), were compared among four groups: thai patients with cholangiocarcinomas (chca), those with calculus cholecystitis (cclt), endemic area victims of traffic accidents, and japanese individuals used as negative contro ...19947943568
cross-sectional study of opisthorchis viverrini infection and cholangiocarcinoma in communities within a high-risk area in northeast thailand.we describe an innovative strategy to quantify risk of cancer associated with varying levels of exposure to chronic parasitic infection through the identification of asymptomatic cases of cholangiocarcinoma within a population-based survey of opisthorchis viverrini infection. stool samples from 12,311 adults over age 24 years from 85 villages in northeast thailand were examined for intensity of liver fluke infection. people from varying egg count categories were selected for ultrasound examinati ...19947960220
parasite-associated morbidity: liver fluke infection and bile duct cancer in northeast thailand.infection with the liver fluke, opisthorchis viverrini, remains a major public health problem in northeast thailand, where approximately one-third of the population is infected. the northeast region is largely populated by laos-descendent thais who enjoy eating raw fish, which harbour the infective stage of the fluke. the parasite has maintained its presence in the population despite the widespread use of praziquantel and dissemination of health education material throughout the region by vigoro ...19947982745
opisthorchis viverrini infection in thailand: symptoms and signs of infection--a population-based study.a population-based study of the clinical, laboratory and ultrasonographic findings in patients suffering from mild or moderate opisthorchiasis in prachinburi province, thailand was conducted in 1990-1992. the effectiveness of treatment with praziquantel at 40 mg/kg body weight was evaluated. after treatment, a long-lasting, marked improvement in the well-being of the study group was observed. symptoms common in opisthorchiasis infection decreased in intensity and the clinical response showed tot ...19947992340
[prevalence of intestinal parasites among thais in israel].stool samples from 93 thais working in israel were examined for the presence of parasites. the overall prevalence of infection by 1 or more species was 74%. opisthorchis viverrini and hookworm were the most prevalent parasites (51.6% and 44.1%, respectively). they were also the parasites most frequently found in mixed infections; about a quarter of the workers were infected with both. other helminths found in only a few cases were: fasciolopsis buski (3 cases), taenia sp. (3), paragonimus sp. (1 ...19948034263
opisthorchiasis control in northeast thailand: proposal for a new approach.opisthorchiasis, i.e. infection with the liver fluke opisthorchis viverrini is an important health problem in thailand and adjacent laos, and its control is therefore of high priority. pilot projects have shown that after praziquantel treatment high re-infection rates occurred within a short period of time. to reduce re-infections it is proposed to couple the time of treatment to the seasonal transmission dynamics and thus treat the population in march when risk of infection for the snail and fi ...19948087151
strong promoting effect of opisthorchis viverrini infection on dimethylnitrosamine-initiated hamster liver.continuous administration of dimethylnitrosamine (dmn) to syrian hamsters infected with the liver fluke, opisthorchis viverrini (ov) results in a 100% incidence of cholangiocellular carcinomas. in a two-stage experiment, however, dosing with liver flukes caused only a few lesions to develop (flavel, d.j. and lucus, s.b. (1983) carcinogenesis, 4, 927]. to clarify this anomaly, syrian hamsters were initiated with 20 mg/kg dmn injected i.p. 19 days prior to 80 ov metacercaria infection. at 45 weeks ...19948180954
identification and potential use of a soluble tumor antigen for the detection of liver-fluke-associated cholangiocarcinoma induced in a hamster model.a liver-fluke-associated cholangiocarcinoma (cca), comparable to that occurring in humans, was induced by exposing opisthorchis viverrini-infected hamsters to dimethylnitrosamine (dmn). tumor masses were removed and histopathologically identified, then one portion was extracted for antigens used in the production of monoclonal antibodies (mabs). the remaining portions were used to establish cca cell lines. the antigens produced and secreted by these cell lines, as well as those originally presen ...19948194877
infection with liver flukes (opisthorchis viverrini, opisthorchis felineus and clonorchis sinensis). 19947715069
changes in serum antibodies to opisthorchis viverrini in humans and hamsters following treatment of opisthorchiasis. 19947872997
association of liver fluke (opisthorchis viverrini) infestation with increased expression of cytochrome p450 and carcinogen metabolism in male hamster liver.synergy between exposure to chemical carcinogens (nitrosamines) and infestation with the liver fluke opisthorchis viverrini has been demonstrated in a hamster model of hepatocarcinogenesis (flavell et al., carcinogenesis 4:927-930, 1983; thamavit et al., carcinogenesis 8:1351-1353, 1987). to elucidate the mechanisms of this interaction we tested the hypothesis that liver parasitism might influence the expression and activity of carcinogen metabolizing enzymes. we found that one, and perhaps more ...19947916996
opisthorchis viverrini: ultrastructure of the tegument of the first-week juveniles and adult flukes.the tegument of one-week-old and adult flukes of opisthorchis viverrini were studied by transmission electron microscopy. the tegument of both stages is composed of a syncytium formed by processes of the tegumental cells lying underneath the outer-circular and the inner-longitudinal muscle layers. the tegument is bounded by trilaminate outer and inner membranes; the former is coated with a thin glycocalyx, while the latter has short basal infoldings. there are 4 forms of tegumental granules, nam ...19947928062
multi-infection with helminths in adults from northeast thailand as determined by post-treatment fecal examination of adult worms.six hundred and eighty-one residents from 16 provinces in northeast thailand who had previously been found positive for opisthorchis viverrini and taenia spp. eggs were given 40 mg praziquantel (bayer, germany), per kg body weight. the total stool output for one to three days was collected and examined for adult worms. the prevalence of o. viverrini in this group was 92.4%. the intestinal flukes echinostoma malayanum, e. ilocanum and e. revolutum were found to be high in males, with 8.3%, 8.1% a ...19947939164
serum antibody response to opisthorchis viverrini antigen as a marker for opisthorchiasis-associated cholangiocarcinoma.the liver flukes opisthorchis viverrini and clonorchis sinensis chronically infect over 30 million people in south-eastern asia, resulting in significant morbidity and a predisposition to cholangiocarcinoma (cca). liver fluke-associated cca carries a poor prognosis, partly because it is often detected at a late and advanced stage. the development of improved diagnostic methods, particularly for early cca, may improve chances of survival and cure. accordingly, we explored the use of immunological ...19947570848
increased nitrosamine and nitrate biosynthesis mediated by nitric oxide synthase induced in hamsters infected with liver fluke (opisthorchis viverrini).we previously reported that increased endogenous nitrosation in human subjects infected with the liver fluke opisthorchis viverrini in north-east thailand could be a risk factor for the development of cholangiocarcinoma. in the present study we examined our hypothesis that this increased endogenous nitrosation is mediated by nitric oxide (no) synthase induced by o. viverrini infestation. syrian golden hamsters experimentally infected with o. viverrini liver fluke excreted in the urine significan ...19947508824
liver fluke infection and cholangiocarcinoma: model of endogenous nitric oxide and extragastric nitrosation in human carcinogenesis.cancers arising during bacterial, viral and parasitic infection provide useful models to investigate the link between inflammation and carcinogenesis. because the inflammatory agent is known, relationships between immune responses, the production of dna-damaging agents, such as nitric oxide, oxygen radicles and n-nitroso compounds, and cancer risk can be explored. this paper first describes the close relationship between infection with the liver fluke, opisthorchis viverrini, and cholangiocarcin ...19947510035
possible protective immunity in human opisthorchiasis.chronic infections with the liver flukes opisthorchis viverrini and clonorchis sinensis affect over 30 million people in southeastern asia. with ongoing exposure, reinfection readily occurs following curative treatment and cumulative infections result in significant morbidity and a predisposition to cholangiocarcinoma. though protective immunity has never been described in human opisthorchiasis, heterogeneity in worm burden occurs and a small number of exposed residents of endemic areas remain a ...19947526321
[cholangiolar carcinoma].cholangiocarcinoma affects both sexes equally, is more prevalent in individuals age 50 to 70. associations with many other diseases are known, in particular with primary sclerosing cholangitis, ulcerative colitis and parasitic infestation (clonorchis sinensis, opisthorchis viverrini). about 95% are histopathologically classified as adenocarcinoma. the localisation of the tumor determines clinical course and prognosis. if the tumor is located above the hepatic duct bifurcation, only one side of t ...19947531268
morphology and ultrastructure of the redia and pre-emergent cercaria of opisthorchis viverrini (trematoda: digenea) in the intermediate host bithynia siamensis goniomphalus (prosobranchia: bithyniidae)].the intramolluscan stages of the human liver fluke opisthorchis viverrini were investigated by light, scanning, and transmission electron microscopy. the morphology of the tegument, and the excretory system of the redia and pre-emergent cercaria as well as glandular cells, tail structure, and the eye spots of the cercarial stage are described. possible environmental adaptations are discussed. the redia is characterized by a tegument which is folded concentrically and covered with densely arrange ...19957550441
opisthorchis viverrini: the tegumental cytoskeleton.the tegumental cytoskeleton of opisthorchis viverrini was observed using both conventional transmission electron microscopy and triton x-100 extraction. the cytoskeletal elements of the newly excysted juveniles, first-week and adult stages are composed of 2 components: firstly, the network of knobbed fibres designated as microtrabeculae which form the principal scaffold of the cytoplasm; and secondly, the microtubules. the microtrabeculae are more densely packed in the newly excysted juveniles a ...19957558564
evaluation of a monoclonal antibody-based enzyme linked immunosorbent assay for the diagnosis of opisthorchis viverrini infection in an endemic area.a monoclonal antibody-based enzyme-linked immunosorbent assay (mab-elisa) was evaluated for its potential in the diagnosis of opisthorchiasis in an area endemic for opisthorchis viverrini infection. the method, based on the detection of the 89-kd o. viverrini metabolic antigen in the feces (coproantigen), was previously estimated to be sensitive enough to detect antigen excreted by a single mature fluke. in the present study, fecal specimens from 207 apparently healthy villagers in northeastern ...19957611558
serum antibody responses in opisthorchiasis.we evaluated an enzyme-linked immunosorbent assay using crude parasite homogenates as a diagnostic test for opisthorchis viverrini infection in humans. serum antibody (ab) responses to o. viverrini adult worm homogenate (awh) and metacercaria homogenate (mh) were studied in 83 infected residents of an opisthorchiasis-endemic area in thailand. elevated levels of ab persisted for over 1 year following curative treatment with praziquantel, and cross-reactivity to o. viverrini awh and mh antigens wa ...19958550296
morphology and ultrastructure of the digestive gland of bithynia siamensis goniomphalus (prosobranchia: bithyniidae) and alterations induced by infection with the liver fluke opisthorchis viverrini (trematoda: digenea).the morphology and ultrastructure of the digestive gland of bithynia siamensis goniomphalus and its alteration by infection with opisthorchis viverrini were investigated by light and electron microscopy. the digestive gland of b. s. goniomphalus was composed of three different cell types: digestive cells, excretory cells, and narrow cells. in infected animals the number of excretory cells increased dramatically. cellular injury in digestive cells as well as in excretory cells following the infec ...19958570585
thiocyanate-independent nitrosation in humans with carcinogenic parasite infection.infection with the liver fluke, opisthorchis viverrini, is a causative agent of cholangiocarcinoma. one possible contributing factor in this carcinogenesis is the chronic, local generation of nitric oxide by inflammatory cells expressing inducible nitric oxide synthase and the production of n-nitroso compounds via the reaction between amines and nitrosating agents derived from nitric oxide. our previous studies provided evidence that nitric oxide synthesis is elevated during human liver fluke in ...19968640916
late complications of infection with opisthorchis viverrini. 19968775739
intestinal parasites among the southeast asian laborers in taiwan during 1993-1994.a large number of foreign laborers are now working in taiwan, the majority coming from southeast asia where parasitic infections are common. since 1992, monitoring the intestinal parasitic infections of these foreigners has been carried out, particularly to prevent the introduction of some of the parasites into taiwan. this paper reports results obtained during the year 1993-1994.19968803301
cross-sectional patterns of hepatobiliary abnormalities and possible precursor conditions of cholangiocarcinoma associated with opisthorchis viverrini infection in humans.the liver fluke, opisthorchis viverrini, is both highly prevalent and closely associated with cholangio-carcinoma in northeast thailand. this study measured associations between intensity of liver fluke infection and nonmalignant hepatobiliary disease diagnosed by ultrasonography among 1, 807 largely asymptomatic adult residents drawn from endemic communities. abnormalities significantly associated with intensity of infection included gallbladder enlargerment in all dimensions, presence of sludg ...19968842118
equivocal evidence of complete carcinogenicity after repeated infection of syrian hamsters with opisthorchis viverrini.the effects of repeated infection with opisthorchis viverrini on liver lesion development in male and female syrian hamsters were investigated over a 1-yr period. ten monthly intragastric applications of 50, 25, 13, or 0 parasite metacercariae resulted in pronounced proliferative and inflammatory lesions involving the first- and second-order ducts in response to the presence of adult worms. despite the development of small numbers of putative preneoplastic areas of cholangiofibrosis and morpholo ...19968864191
cholangiocarcinoma in patients with opisthorchiasis.cholangiocarcinoma is very common in areas endemic for the liver fluke opisthorchis viverrini. survival after surgical treatment of cholangiocarcinoma associated with opisthorchiasis was studied prospectively in 30 patients, all of whom resided in an endemic area. the median age was 52 (range 32-69) years and twenty-five patients were men. seven patients had their tumours removed, four with concomitant liver resection. twenty-two patients underwent palliative biliary bypass procedures to a segme ...19968869303
induction of cytochrome p450 2a6 expression in humans by the carcinogenic parasite infection, opisthorchiasis viverrini.the purpose of this study was to examine in vivo the activity of cytochrome p450 (cyp) 2a6, an enzyme capable of activating carcinogens, including n-nitrosodimethylamine, in humans with the carcinogenic liver fluke infection, opisthorchiasis viverrini, before and after treatment with the antiparasitic agent, praziquantel. coumarin hydroxylase activity of cyp 2a6 was assessed by administering a probe drug, coumarin, and measuring its metabolite, 7-hydroxycoumarin, in urines collected between 0-2 ...19968896890
prevalence of intestinal parasitic infection among children in two villages in lao pdr.the prevalence of intestinal parasitic infection among 128 children under 15 years old in two villages in khammouane province, southeastern lao pdr, was investigated. overall prevalence of helminth infection was 77.3%; the prevalence was 64.8% in children under 6 years, 88.5% in those aged 6-10 years and 81.8% in the age group above 11 years. the prevalent helminths found in the subjects were ascaris lumbricoides (48.4%), trichuris trichiura (43.8%), hookworm (37.5%) and opisthorchis viverrini ( ...19969185270
opisthorchis viverrini: effect of praziquantel on the adult tegument.ultrastructural changes of the tegument of adult liver flukes, opisthorchis viverrini, after in vitro incubation in minimal essential medium containing 0, 0.1, 1.0 and 10.0 micrograms/ml of anthelminthic praziquantel for 5, 15, 30, 45 and 60 minutes were investigated by scanning (sem) and transmission (tem) electron microscopy. sem observations showed that the surface damage was composed of blebbing due to the swelling of microvilli, followed later by the disruption of these structures to form l ...19969279994
opisthorchis viverrini: the effects of colchicine and cytochalasin b on the adult tegument.the roles of the tegumental cytoskeleton were tested by treating adult flukes with colchicine and cytochalasin b. following a short incubation period (10-20 minutes), colchicine disrupted microtubules in the tegumental cells' processes which, in turn, affected the transport of dense granules from the cells' soma to the tegument; as a result some of these granules were fused together to form membrane-bound vacuoles. in addition, at many spots microtrabeculae were also depolymerized, which resulte ...19969279995
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